Ev2 shims: Calculate and provide the checksums for the Ev2 handlers.
Ev2 shims: Calculate and provide the checksums for the Ev2 handlers.

* subversion/libsvn_delta/compat.c
  (path_checksum_args): New.
  (process_actions): Handle and provide the checksum when required APIs.
  (ev2_apply_textdelta): Calculate the text delta and store it for later.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion